Juice Debittering: Basic Science, Optimization, and Recent Advances

Bitterness such as Naringin in Grapefruits and Limonin in all Citrus fruits have a strong influence on consumers’ choices for their favorite juices. There have been many methods from ultrafiltration to biocatalysis used to lower such bitter compounds and make the juices more desirable by the consumer. One major tool for such debittering operation is the use of synthetic adsorbents which will be discussed in this paper. Ion exchange resins and adsorbents have been used for over a century in various food applications to concentrate flavors, decolorize juices, and enhance the quality of the final product. These types of resins are being synthesized to specific parameters to distinguish them from other tools. Mitsubishi Chemical’s work on optimizing their synthetic adsorbents for high bitterness removal from citrus juice was investigated. Parameters such as the base matrix structure, pore size and distribution, as well as the effect of surface area were studied. As the FDA has strict definitions about the appropriate resin chemistry that can be used in a food application (21 CFR 173.65), progress in new resin chemistry was limited by such regulations. This paper discusses the use of the original Sepabeads SP70 which was introduced into the market about 20 years ago, to the high capacity resin, Sepabeads SP700, which was introduced 10 years ago, and finally, to the Sepabeads SP710, which is the current optimized version of 20 years of research work. Mitsubishi Chemical’s resins were compared to other resins in the industry for the removal of naringin, limonin, and 8-hydroxyfuranocoumarin (furanocoumarins are compounds that affects the proper absorption of certain medications). Proper regeneration and rejuvenation of these resins were outlined. Paper published with permission.

Press Liquor Filtration

Usually a Citrus Engineering Conference presentation before this group is done to report some advance in citrus related technology. This paper, however, is limited to suggesting an area where significant benefits might result from further study and testing. This paper has to do with improving the thermal efficiency of citrus feedmills. The idea presented can also help reduce cleaning expenses. The concept has to do with filtering press liquor ahead of a Waste Heat Evaporator (WHE). Work done so far is not definitive, and it is clear that further testing is required. The paper is focused on a machine known variously as the Turbo Filter or Fiber Filter. This is unfortunate because other filtration equipment may be even more effective or commercially justifiable. The basic premise of this paper, which needs to be demonstrated, is that improved filtration of press liquor results in lower viscosity fluid in the WHE. In turn this allows the WHE to produce higher Brix molasses. The result of this are improved thermal efficiency of the citrus feedmill. Paper published with permission.

Water Conservation and Wastewater Load Reduction in Citrus Processing

In the state of Florida, the vast majority of potable water comes from groundwater supplies. Salt water intrusion into groundwater aquifers coupled with variable rainfall and periodic droughts are affecting the availability of this supply. As the supply of potable groundwater in Florida becomes less and less available, it is crucial for municipalities and industry alike to take the initiative to protect diminishing water resources through conservation. In addition, increased scrutiny from state and federal regulators on effluent wastewater discharges from industrial facilities such as citrus processing plants has resulted in tighter effluent discharge standards, limits to organic loadings on land application and increased wastewater pretreatment requirements. These trends are expected to continue and citrus processors are faced with the reality that these tightening requirements are making wastewater treatment an even more critical part of their operations. Paper published with permission.